| Abstract: | The wasp genera included in the Polysphincta genus-group develop exclusively as koinobiont ectoparasitoids of spiders, an unusual pattern within Hymenoptera. All known species of Hymenoepimecis attack orb-web spiders and Hymenoepimecis argyraphaga was previously described inducing a sudden modification of its host's web-building behaviour. Information on parasitoid–host interactions and even on host identities for most members of the genus-group, however, remain scarce. In this study we describe two new species of Hymenoepimecis and present information on their hosts, spiders of the genera Leucauge (Tetragnathidae) and Manogea (Araneidae). Cocoon webs of both host species are distinct from their normal webs. The modified cocoon web of Leucauge roseosignata constructed under the influence of Hymenoepimecis japi sp. nov. is very similar to the cocoon web described for Leucauge argyra. It is composed of three axes, including several radial threads each, and a hub used by the larva to attach the cocoon's suspension line. Spiral viscous threads, present in normal webs and in webs of parasitized spiders carrying larvae in the initial instars, are absent in cocoon webs. In the cocoon web of Manogea porracea the horizontal sheet is poorly structured and the cocoon is attached far from the spider's normal resting position, in an area composed of a densely tangled structure. |
